At present, one relatively scientific protect device of commercially available common shredders is to utilize a coded disc mounted at the end of the motor shaft to detect the rotational speed of the working motor decreased due to insufficient torsion resulting from the reaction force of many pieces of paper to be shredded after they are fed into the cutting blades, so as to control the motor to stop through the control circuit of the shredder to protect the motor and driving gears.
Because the above protection device is to stop the motor when the motor decelerates or can not rotate, so as to protect the motor and driving gears, and at that time the motor has been under the overload operation, that such process occurs many times would undoubtedly result in the failure of the motor or breaking the driving gears, to make the machine can not work completely.
Another relatively scientific protect device of commercially available common shredders is to utilize an optical induction assembly mounted at the end of the contact member to detect the displacement of the coded disc resulting from the contact member pushed by many pieces of paper to be shredded before they are fed into the cutting blades, so as to control the motor to stop through the control circuit of the shredder when the change exceeds the predetermined value of the machine, to protect the motor and driving gears.
For this protection device utilizes an optical component to detect the displacement of the coded disc, and much dust would generate during the operation of the shredder, the dust would affect the detection accuracy of the optical induction assembly, namely the accuracy of the thickness of the paper, so as to result in inaccuracy and misjudgment to cause the motor to be under the overload operation, then that such process occurs many times would undoubtedly result in the failure of the motor or breaking the driving gears, to make the machine can not work completely.
The above mentioned problems of paper jam, overload and tooth breaking are main puzzles that cause shredders to be repaired frequently and used inconveniently by users.
In order to solve the above existing problems and shortcomings, it is very necessary to improve further, even innovate the protection device of common shredders.